Analyte detection in physiological fluids, e.g. blood or blood derived products such as plasma, is of ever increasing importance to today's society. Analyte detection assays find use in a variety of applications and settings, including the clinical laboratory testing, home testing, etc., where the results of such testing play a prominent role in diagnosis and management in a variety of disease conditions. Analytes of interest include glucose for diabetes management, cholesterol for monitoring cardiovascular conditions, and the like. In response to this growing importance of analyte detection, a variety of analyte detection protocols and devices for both clinical and home use have been developed.
Many analyte detection assays are based on the production of hydrogen peroxide and the subsequent detection thereof. Analytes that may be detected using such assays include: cholesterol, triglycerides, glucose, ethanol and lactic acid. For example, glucose is quantitated using such assays by first oxidizing glucose with glucose oxidase to produce gluconic acid and hydrogen peroxide. The resultant hydrogen peroxide, in conjunction with a peroxidase, causes the conversion of one or more organic substrates, i.e. an indicator, into a chromogenic product, which product is then detected and related to the glucose concentration in the initial sample.
Hydrogen peroxide based assays, such as the glucose assay described above, are subject to problems which result from the presence of erythrocyte components, e.g. catalase, that interfere with the hydrogen peroxide based reaction and therefore alter (for example reduce) the signal that is ultimately obtained and used to derive the analyte concentration. As such, many different protocols have been developed which are designed to at least reduce the potential analytical error that is introduced in the assay through the release of interfering erythrocyte components via hemolysis. Such protocols include: filtration, filtration combined with the addition of inhibitors, filtration and trapping of erythrocytes, and the use of asymmetric non-hemolyzing membranes.
While such methods can partially remove the analytical error introduced by hemolysis, they are not entirely satisfactory. For example, filtration typically requires longer assay times and larger sample sizes than is desirable.
As such, there is continued interest in the development of new devices and methods for use in analyte detection. Of particular interest would be the development such a device and method which minimized the analytical error originating from hemolysis and yet provided a rapid assay time from a small sample volume.
Relevant Literature
U.S. patent documents of interest include: U.S. Pat. Nos. 4,297,238; 5,258,047; 5,563,042; 5,753,452; 5,789,255; 5,843,691; 5,866,349; 5,968,836 and 5,972,294. Also of interest are: WO 90/12889; WO 90/12890; JP 3180762; JP 62296987; and EP 0 638 805.